Conditions in Swamps 95 



Conditions of life — In the shoal vegetation-choked 

 waters of marshes there is httle chance for the formation 

 of currents and Httle possibility of disturbance by wind. 

 Temperature conditions change rapidly, however, owing 

 to the heat absorbing and heat radiating power of the 

 black plant-residue. The diurnal range is very great, 

 water that is cool of a morning becomes repellantly hot 

 of a summer afternoon. Temperatures above 90° F. 

 are not then uncommon. Unpublished observations 

 made by Dr. A. A. Allen in shoal marsh ponds at the 

 Cornell Biological Field Station throughout the year 

 1909, show a lower temperature at the surface of the 

 water than in the bottom mud from December to April, 

 with reverse conditions for the remainder of the year. 

 The black mud absorbs and radiates heat rapidly. 



Conditions peculiar to marshes, swamps and bogs are 

 those due to massed plant remains more or less per- 

 manently saturated with water. Water excludes the 

 air and hinders decay. Half disintegrated plant 

 fragments accumulate where they fall, and continue 

 for a longer or shorter time unchanged. According to 

 their state of decomposition they form peat or muck. 



In peat the hard parts and cellular structure of the 

 plant are so well preserved that the component species 

 may be recognized on microscopic examination. To 

 the naked eye broken stems and leaves appear among 

 the finer fragments, the whole forming a springy or 

 spongy mass of a loose texture and brownish color. 

 The color deepens with age, being lightest immediately 

 under the green and living vegetation, and darkest in 

 the lower strata, where always less well preserved. 



The water that covers beds of peat acquires a brown- 

 ish color and more or less astringent taste due to in- 

 fusions of plant-stuffs. Humous acids are present in 

 abundance and often solutions of iron sulphate and 

 other minerals. 



